Tribological properties of carbon/carbon composites with various pyrolytic carbon microstructures

Tribological properties of carbon/carbon composites with various pyrolytic carbon microstructures have been investigated. Three kinds of samples characterized by rough laminar (IT-a), smooth laminar (IT-b) and duplex microstructure containing both rough laminar and smooth laminar (TG-c) structures were used in the current study. The minimum coefficient of friction was observed for the IT-b sample, for which the amount of abrasion due to oxidation was the highest because it had the highest hardness and because no compact smooth film formed on the friction surface. Continuous film formation on the friction surface is dominant in the samples with rough laminar structures (IT-a and TG-c) for their hardnesses below a certain value. The coefficient of friction is associated with the interfacial shear strength and the surface hardness of carbon/carbon composites and is relatively stable when the friction film formation and abrasion wear reach an equilibrium state.